Nowadays, computer networks are increasingly applied more and more deeply and widely, communication between people is no longer limited by a region and a distance. However, after a relatively long distance is spanned, a network delay is obviously increased. Such delay mainly includes a delay for transmitting a data packet on a network, a delay for a data packet to wait in a queue and be processed on a transmission device (such as a router), and so on. A delay for transmitting a data packet on a wide area network (Wide Area Network, WAN) may reach tens of or even hundreds of milliseconds.
In an actual application, data packet transmission can be started only after a transport control protocol (Transport Control Protocol, TCP) handshake process is undergone. The TCP handshake process is as shown in FIG. 1, and includes the following steps: Step (1): A client sends a server a handshake request packet carrying transmission parameters that need to be negotiated, where the parameters that need to be negotiated and are carried in the handshake request packet sent by the client include parameters such as an initial sequence number (Initial Sequence Number, ISN) and a maximum segment size (Maximum Segment Size, MSS) of the packet sent by the client and a receive window size of the client; step (2): After receiving the handshake request packet of the client, the server sends the client a handshake response packet carrying negotiated parameters, where the negotiated parameters carried in the handshake response packet sent by the server include parameters such as an ISN and a maximum segment size MSS of the packet sent by the server and a receive window size of the server, and both negotiated parameters SYN and ACK carried in the handshake response packet sent by the server are set to 1, indicating that the handshake request packet sent by the client has been received by the server; step (3): After receiving the handshake response packet sent by the server, the client sends an acknowledgement response packet (a carried ACK is set to 1, indicating that the client has received the handshake response packet of the server) to the server, thereby completing the TCP handshake process, so that data packet transmission may be started between the client and the server.
It can be known from the foregoing description that, a data packet can be transmitted only after a TCP handshake process is completed. However, in the TCP handshake process, a round-trip time (Round-Trip Time, RTT) delay of a packet on a network also exists, and a data packet transmission delay may be significantly increased due to existence of the RTT delay.